Electric fuse



Feb. 27, 1940. H, JAEDIKE 2,191,793

ELECTRIC FUSE Filed Feb. 7, 1939 ATTORNEYS Patented Feb. 27, 1940 UNITED STATES PATENT oFFIcE 6 Claims.

This invention relates generally to fuses which are employed in electric circuits for imposing a predetermined limit on the load or current andv pertains more particularly to improvements in electric fuses of the type which areV known as plug or cartridge fuses.

The invention broadly comprehends an improved electric fuse which embodies relatively few and simple parts, more compactly arranged and of lighter weight and capable of more eccnomical production than those heretofore produced.

More specifically the invention resides in an improved electric fuse in which the parts thereof are stamped or otherwise fashioned from sheet material thereby avoiding the necessity o f molding, casting, spinning or other relatively expensive operations and wherein the parts are assembled in laminated form by means of rivets kto provide a closely confined compact structure possessing a high factor of safety and stability.

With the above and other objects in view, the invention is set forth in greater detail in the following specification and illustrated in the accompanying drawing, in which:

Fig. l is a front View of a plug type fuse constructed in accordance with the| invention and illustrating the same actively positioned ink a socket.

Fig. 2 is `a side edge view thereof.

Fig. 3 is a sectional view therethrough taken approximately on the line 3-3 of Fig. 2.

Fig. 4 is a bottom plan view thereof.

Fig. 5 is a perspective View of a modified formof the invention illustrating a cartridge type fuse.

Fig. 6 is a sectional View therethrough.

Referring to the drawing by characters of reference and particularly to the form of the invention illustrated in Figs. 1 to 4 inclusive, A designates generally a plug type fuse and B a socket for receiving the same, which socket includes a threaded conducting rim` I0 constituting one terminal of the fuse socket and a centrally disposed Contact |I insulated therefrom and serving as the other terminal of the fuse socket.

The fuse A includes a fusible element I5 which is fashioned from sheet material and of substantially U-shaped configuration providing a pair of legs I6 and I1 joined by a bight portion I8. A pair of side plates I9 and 20 which are formed of fiat sheets of insulation material are arranged on opposite sides of the fusible element I5 soy as to dispose the fusible element therebetween and Wholly Within the confines of the side plates so (Cl. o-130) that the fusible element is spaced from and within the marginal edges thereof.

Either one or both of the side plates are prov vided with window openings 2|, in the present instance both plates being provided with Window openings disposed in alignment with each other so as to display therethrough the bight portion |8 of the fusible element I5. The side plates I9 and 20 are secured together with the fusible element I5 interposed therebetween by means of rivets 22, one of which passes through the leg I6.

A contact foot 23 of conducting material is also interposed between the enlarged free end portion 24 of the leg I1 and one of the side plates and is secured in place by means of a rivet 25 passing through both of the side plates, the enlarged free end portion 24 of the fusible element and the contact foot 23, which latter protrudes be'- yond the end edges of the cover plates and is formed with an angularly disposed terminal 26. A strip of conducting material 21 is arranged transversely and exteriorly of one of the side plates and is secured thereto by opposite rivets 22, one of which rivets extends through the leg I6 of the fusible element I5. l

TheI strip 21 is provided with angularly disposed opposite ends 28 having lenlarged' concave-convex finger pieces 29 defining at the opposite side edges of the fuse structure resilient means for cooperative engagement within the threaded conducting rim I0 at diametrically opposite sides thereof to frictionally retain the fuse A Within the socket B against accidental or unintentional displacement, while permitting of the forceable removal thereof.

In order to assist in the retention of the fuse plug within the socket B, the finger pieces are formed with outwardly protruding teats 30 which more eifectually engage the threads of the conducting rim of the socket. It Will be* observed that the strip 21 together with its integral angularly disposed portions and finger pieces 29 are also formed of sheet material as is the contact foot 23.

In practice, the fuse will preferably include, as illustrated, a pair of transparent panels of insulation sheet material 3| and 32 which are respectively interposed between the opposite sides of the fusible element I5 and the side plates |9 and 20 in the region of the window openings 2|. This exposes the bight portion I8 of the fusible element to View, while covering and protecting the same.

As illustrated, the corners of the transparent panels 3| and 32 are cut away or notched as at 33 to engage with the rivets 22 so as to retain the panels in place between the side plates I9 and 20. The fuse may also be provided with a shield piece 34 which is made of sheet insulation material, slotted as at 35 and frictionally fitted over the fuse body and engaging with the transverse strip 21 so as to protect the fingers when the fuse is grasped by the upper portion thereof to effect the insertion of the lower end Within the socket B or the removal of the same therefrom.

In use it will be apparent that when the lower end of the fuse plug is inserted within the threaded conductor rim l of the socket B, theterminal 26 of the contact foot is brought into engagement with the center co-ntact il of the socket, while the spring finger pieces frictionally retain the fuse plug in place and at the same time serve to effect electric contact with the conducting rim so that the current flows from the central Contact H through the contact foot 23, the leg I1 of the fusible element I5, thence through the bight i8, the leg i6 thereof, the rivet 22, the strip 21 and the conducting rim I0 of the socket. 'I'he intermediate portion of the bight I8 is provided with oppositely disposed notches which, in event of an overload in the circuit, will cause fusing at this, the weakest part of the fusible element, where the blowing of' the fuse may be readily observed through the window openings and transparent panels.

In the modified form of the invention illustrated in Figs. and 6 of the drawing, the fuse is of the character ordinarily known as the cartridge type and is adapted to be used in conjunction with a cartridge type fuse socket. In this form of the invention, the side plates 35 and 36 are of substantially T-shaped formation and are constructed of flat sheets of insulation material with the upwardly protruding stem portions 31 formed with aligned window openings 33. In this instance, the fusible element 39 is of substantially U-shaped formation and interposed between the side plates with the bight portion 4l) thereof extending across the window openings 38 and with the depending leg portions 4| and 42 thereof formed respectively with outwardly directed feet 43 and 44.

Mating pairs of contact elements 45 and 46 are located on opposite sides of the lower end portions of the side plates and are attached to the fuse body by means of rivets 41 and 48 which extend through the contact elements, the side plates and the feet 43 and 44 of the fuse element, the rivets serving in addition to means for holding the parts in assembled relation, as means for electrically connecting the contacts to the opposite ends of the fuse element. 'I'he contact elements 45 and 46 are provided with resilient substantially semi-cylindrical extremities 49 and 5I] which are adapted to be received within the cliplike terminals of the usual cartridge type fuse socket.

Preferably transparent panels 5| of insulation sheet material are arranged on opposite sides of the fusible element and interposed between the saine and the opposite side plates so as to cover and protect the bight portion 40 of the fuse element which is displayed through the window openings 3S.

What is claimed is:

l.. An electric fuse plug including a flat elongated laminated body structure comprising a flat metallic fusible strip, a pair of fiat non-conductor side plates disposed on opposite sides of the fusible strip in covering relation therewith, resilient sheet metal Contact members for engagement respectively with the opposite terminals of a plug type socket, one of said contact members having resilient wing portions located respectively at the opposite side edges of the body and the other having a resilient wing portion located at one end edge of the body and the wing portions of one contact member being disposed in parallel planes perpendicular to the plane of the body with the wing portion of the other contact mem.- ber disposed in a plane perpendicular to the wings of the said first contact member and perpendicular to the body, and a common means for securing said contact members respectively to the opposite ends of the fusible strip and for holding the side plates in covering relation with the fusible strip.

2. In an electric fuse plug, a 'at elongated laminated body structure including a fiat metallic fusible strip, a pair of fiat non-conductor side plates disposed on opposite sides of' the fusible strip in coveringv relation therewith, sheet metal contact members for engagement with the opposite terminals of an electric socket, one of said contact members including offset resilient portions at lthe opposite side edges of the body structure disposed in a plane perpendicular to the plane thereof and adapted to engage with the threads of the conducting rim of a plug type socket for releasably retaining the plug in the socket, and a common means for securing said Contact members respectively to the opposite ends of the fusible strip and for holding the side plates in covering relation with the fusible strip.

8. In an electric fuse plug, a flat elongated body structure including a flat metallic fusible strip, a pair of flat non-conductor side plates disposed on opposite sides of the fusible strip in covering relation therewith, sheet metal contact members for engagement with the opposite terminals of an electric socket, one of said contact members including a metallic strip disposed transversely upon one of said side plates and having offset resilient end portions at the opposite side edges of the body structure disposed in parallel planes perpendicular to the plane of the body structure and adapted to engage within the conducting rim of a fuse socket at diametrically opposite points thereof for releasably retaining the plug in the socket, the other contact member being disposed at the end edge of the body structure and having an angulated terminal disposed in a plane perpendicular to the plane of the body structure and to the planes of the end portions of the other contact member, and a common means for securing said contact members respectively to the opposite ends of the fusible strip and for holding the side plates in covering relation to the fusible strip.

4. An electric fuse including a laminated body consisting of outer plates of flat sheet insulation material at least one of which plates is provided with a window opening, a fusible element of flat sheet material interposed therebetween and having a portion thereof displayed through the window opening, a transparent panel of insulation material arranged between said fuse element and the plate in the region of the window opening to cover the portion of the fuse element displayed therethrough, spaced sheet metal contact elements disposed exteriorly of the body and each having angulated terminal portions disposed in planes perpendicular to each other and perpendicular to the plane of the body for engaging with opposite terminals of a fuse socket, and rivets extending through said laminated body for securing the plates, the fusible element and the contact elements in assembled relation and for electrically connecting said contact elements with the fusible element. e

5. An electric fuse including a laminated body consisting of outer plates of :flat sheet insulation material at least one of which plates is provided with a window opening, a fusible element of at sheet material interposed therebetween and having a portion thereof displayed through the window opening, a transparent panel of insulation material having notched corners arranged between said fuse element and the plate in the region of the window opening to cover the portion of the fuse' element displayed therethrough, spaced sheet metal contact elements disposed exteriorly of the body and each having angulated terminal portions disposed in planes perpendicular to each other and perpendicular to the plane of the body for engaging with opposite terminals of a fuse socket, and rivets extending through said notched corners, the side plates, the fusible element and the contact elements for securing the same in assembled relation and for electrically connecting said contact elements with the fusible element.

6. An electric fuse including a flat laminated body consisting of outer plates of flat sheet insulation material at least one of which plates is provided with a Window opening, a fusible element of flat sheet material interposed therebetween and having a portion thereof displayed through the Window opening, a transparent panel of insulation material arranged between said fuse element and the plate in the region ot the window opening to cover the portion of the fuse element' displayed therethrough, spaced pairs oi sheet metal contact elements disposed exteriorly of and on opposite sides of the body and having flat bases and mating semi-cylindrical resilient extremities each reversely curved to dispose the free end thereof adjacent the free end of the base and which pairs of contact elements are adapted for engagement with opposite terminals of a cartridge type fuse socket, and rivets extending through said outer plates, the opposite ends ofthe fusible element, and the bases of the contact elements for securing the same in assembled relation and for electrically connecting said contact elements with the fusible element.

HENRY JAEDIKE. 

